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(lib)unarr

(lib)unarr is a decompression library for RAR, TAR, ZIP and 7z* archives.

It was forked from unarr, which originated as a port of the RAR extraction features from The Unarchiver project required for extracting images from comic book archives. Zeniko wrote unarr as an alternative to libarchive which didn't have support for parsing filters or solid compression at the time.

While (lib)unarr was started with the intent of providing unarr with a proper cmake based build system suitable for packaging and cross-platform development, it's focus has now been extended to provide code maintenance and to continue the development of unarr, which no longer is maintained.

Getting started

Prebuilt packages

From OBS

.deb package .rpm package

Building from source

Dependencies

(lib)unarr can take advantage of the following libraries if they are present:

• bzip2
• xz / libLZMA
• zlib

More information on what library is used for which purpose can be found in the description for embedded builds.

CMake

mkdir build
cd build
cmake ..
make

... as a static library

cmake .. -DBUILD_SHARED_LIBS=OFF

... with 7z support (see note below)

cmake .. -DENABLE_7Z=ON

By default, (lib)unarr will try to detect and use system libraries like bzip2, xz/LibLZMA and zlib. If this is undesirable, you can override this behavior by specifying:

cmake .. -DUSE_SYSTEM_BZ2=OFF -DUSE_SYSTEM_LZMA=OFF -DUSE_SYSTEM_ZLIB=OFF

Install

make install

Embedded build

Make sure your compiler is C99 compatible, grab the source code, copy it into your project and adjust your build system accordingly.

You can define the following symbols to take advantage of third party libraries:

Symbol	Required header	Required for (format/method)
HAVE_ZLIB	zlib.h	faster CRC-32 and Deflate
HAVE_BZIP2	bzlib.h	ZIP / Bzip2
HAVE_LIBLZMA	lzma.h	ZIP / LZMA, XZ(LZMA2)
HAVE_7Z	7z.h	7Z / LZMA, LZMA2, BCJ
_7ZIP_PPMD_SUPPPORT		7Z / PPMd

Make sure the required headers are present in the include path.

Usage

Examples

Check unarr.h and unarr-test to get a general feel for the api and usage.

To build the unarr-test sample application, use:

cmake .. -DBUILD_SAMPLES=ON

Limitations

Unarr was written for comic book archives, so it currently doesn't support:

• password protected archives
• self extracting archives
• split archives

7z support

7z support is currently limited and has to be explicitly enabled at build time.

This is due to a known performance problem in the ANSI-C based 7z extraction code provided by the LZMA SDK that limits its usefulness for large files with solid compression (see zeniko/unarr#4).

Fixing this problem will require modification or replacement of the LZMA SDK code used.